BS 4995:1973

Cooperating organizations
Foreword
Recommendations
1. Scope
2. Definitions
3. Preferred conditions
4. Test conditions for the measurement of veiling
    glare index
5. General requirements
6. Detailed equipment requirements
7. Specification of measurement conditions
8. Points requiring special attention during veiling
    glare measurements
9. Presentation of results
10. Practical experimental techniques
Appendices
A. Preferred format for veiling glare test
B. Other methods of measuring veiling glare index
Figures
1. Equipment for test conditions A and B
2. Equipment for test condition C1
3. Equipment for test condition C2

Laboratory techniques for measuring VGI are described in general terms and recommendations are made regarding the performance of the main subunits of the equipment. Standard methods of specifying conditions of test and of expressing the results. Gives guidelines for the operation of VGI measuring equipment to facilitate the obtaining of accurate results.

This British Standard adopts veiling glare index (bright field) (VGI) as a measure of the veiling glare characteristics of an optical system. Laboratory techniques for measuring VGI are described in general terms and recommendations are made regarding the performance of the main sub-units of the equipment.

Standard methods of specifying conditions of test and of expressing the results are given, while to assist in the intercomparison of VGI figures, four standard test conditions are specified. It is also the purpose of this standard to give guide lines for the operation of VGI measuring equipment such that accurate results may be achieved.